Recently, electronic devices such as personal digital assistant (PDA), a mobile communication terminal, a vehicle navigation, and the like, form a large market. Technical goals to be pursed of the above-described electronic devices mainly include thin thickness, light weight, low power consumption, higher resolution, and high brightness, and the like.
Meanwhile, in electronic devices equipped with a touch screen or a touch panel switch in an input operation portion, a transparent conductive plastic film is used for light weight, breakage prevention, and the like. An example of the transparent conductive plastic film includes a film having a polyethylene terephthalate (PET) film as a substrate, and having a conductive layer such as an indium tin oxide (ITO) formed on one surface of the PET film, wherein the film is stacked on a conductive glass, a reinforcement material, a decorative film, and the like, by an adhesive layer.
In the touch screen or the touch panel, adhesive used for attachment of a transparent conductive film requires various physical properties such as a step-absorbing property capable of absorbing a printing step by the decorative film; and durability capable of inhibiting occurrence of white turbidity phenomenon when the touch screen or the touch panel is exposed to severe conditions such as high temperature or high humidity conditions.